Chapter 8: Luminescence

Question 1

Luminescence Spectroscopy

Answer 1

Emission of light by sample

Question 2

Types of Luminescence

Answer 2

-Fluorescence
-Phosphorescence
-Chemiluminence/Bioluminence

Question 3

Fluorescence

Answer 3

Happens quickly after the absorption of a photon (nanosecond to microsecond)

Question 4

Phosphorescence

Answer 4

Happens more shortly after absorption of a photon (milliseconds to minutes).

Question 5

Chemiluminescence/Bioluminescence

Answer 5

Excitation arises from a chemical reaction followed by emission by emission.

Question 6

You can ____ an electron, but can never ____ an electron.

Answer 6

-promote
-flip

Question 7

True or False: Most molecules do NOT have singlet ground states.

Answer 7

False.

Question 8

Excited States: T and S

Answer 8

T: Lower energy
S: Higher energy

Question 9

Photoabsorption

Answer 9

Absorption of a photon from ground vibronic (electronic/vibrational) in S0 to vibrational levels in excited states (femtoseconds 10^-15)

Question 10

Vibrational Relaxation

Answer 10

Collisions within electronic state (picoseconds 10^-12)

Question 11

What does radiative decay process?

Answer 11

Fluorescence (S to S) and (T to T)

Question 12

What does non-radiative decay process?

Answer 12

Phosphorescence (S to T) and (T to S)

Question 13

True or False: In Fluorescence the excitation wavelength does not equal to the absorption wavelength.

Answer 13

True.

Question 14

Quencher

Answer 14

Something that suppresses fluorescence.

Question 15

What makes a good quencher?

Answer 15

Something that has lone pairs of electrons.

Ex: O2 and halogens.

Question 16

What percent of molecules fluoresce?

Answer 16

1%

Question 17

How do you remove O2 from fluorescent solution?

Answer 17

1) Bubble argon
2) Vaccum manifold
3) Freeze/Pump/Thaw